The present invention relates to printing devices. More particularly, the present invention relates to an apparatus and method for reducing print media edge margin tolerances in a printing device with one or more supplies of print media.
Printing devices, such as inkjet printers and laser printers, use printing composition (e.g., ink or toner) to print text, graphics, images, etc. onto a print medium in a printzone of the printing device. Inkjet printers may use print cartridges, also known as xe2x80x9cpensxe2x80x9d, which shoot drops of printing composition, referred to generally herein as xe2x80x9cinkxe2x80x9d, onto a print medium such as paper, transparencies or cloth. Each pen has a printhead that includes a plurality of nozzles. Each nozzle has an orifice through which the drops are fired. To print an image, the printhead is propelled back and forth across the page by, for example, a carriage while shooting drops of ink in a desired pattern as the printhead moves. The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as thermal printhead technology.
In a current thermal system, a barrier layer containing ink channels and vaporization chambers is located between an orifice plate and a substrate layer. This substrate layer typically contains linear arrays of heating elements, such as resistors, which are energized to heat ink within the vaporization chambers. Upon heating, the ink in the vaporization chamber turns into a gaseous state and forces or ejects an ink drop from an orifice associated with the energized resistor. By selectively energizing the resistors as the printhead moves across the print medium, the ink is expelled in a pattern onto the print medium to form a desired image (e.g. picture, chart and/or text).
Printing devices typically include one or more print media input devices, such as print media input trays for sheets of print media or input racks for rolls of print media. These input devices feed a supply of print media into the printzone of the printing device where printing composition is deposited on the print media to form the desired image.
Ideally, the print media is fed into the printzone each time at the same location to help assure that the image is exactly placed on the print media. However, due to design and manufacturing tolerances, such exact positioning is not possible. Instead, the supply of print media is actually positioned in a range of distances around the ideal or desired location. If this range is wide enough, then the output print quality of images from a printing device suffers. In certain instances, the output print quality may be illegible and require a new print job to be run which is wasteful and time consuming, particularly for large print jobs or print jobs that are left to run unattended, such as those that are done overnight. As a consequence, printing device throughput is also reduced. Also, usable print area may be wasted depending on where the print media is actually placed in the printzone. These problems are only exacerbated as the number of print media input devices increases because each input device has a different range of distances around the ideal or desired location, which range of distances tends to increase as an input device is positioned further from the printzone.
One way in which to help alleviate these problems is to attempt to minimize design and manufacturing tolerances which should reduce the range of distances around the ideal or desired location. This approach, however, is not without its own problems including increased complexity of both design and manufacture, as well as increased cost for such a print media input device. Again these problems are only exacerbated as the number of input devices increases.
Another approach to help alleviate these problems is to sense the edge of a print medium each time the print medium is feed into a printzone and adjust the position of where printing begins based on where the edge is located in the printzone. Such an approach, while greatly increasing image placement accuracy on a print medium and, therefore, printing device output print quality, has the drawback of decreasing printing device throughput because of the time required to sense the edge of the print medium in the printzone each time a new print medium enters the printzone, and adjust image placement accordingly.
A further approach to help alleviate these problems is to use print media registration devices that position print media correctly in the printzone. This approach, as with those that attempt to minimize design and manufacturing tolerances, is not without its own problems including increased complexity of both design and manufacture, as well as increased cost for such a print media input device. As discussed above, such problems are only exacerbated as the number of input devices increases.
Alleviation of these problems would be a welcome improvement, thereby helping minimize delay in the completion of printing tasks, helping maximize printing device throughput, and helping prevent instances of waste of print media. Accordingly, the present invention is directed to solving those problems caused by positioning of print media in a range of distances around an ideal or desired location in the printzone of a printing device. The present invention accomplishes this objective by providing an apparatus and method for reducing edge margin tolerances in a printing device with one or more supplies of print media while at the same time attempting to minimize the impact on printing device throughput.
An embodiment of a method in accordance with the present invention for use in a printing device, the printing device having a supply of print media and being configured to feed the supply of print media into a printzone where printing composition is deposited on the supply of print media, includes determining a range of positions of the supply of print media in the printzone. The method additionally includes determining a median position of the supply of print media in the printzone and adjusting a position in the printzone for the supply of print media where printing composition is deposited based on the determined median position of the supply of print media in the printzone.
In the above-described embodiment of a method in accordance with the present invention, the range of positions of an edge of the supply of print media may be determined, as can the median position of the edge of the supply of print media in the printzone. Based on the determined median position of the edge of the supply of print media in the printzone, the position in the printzone for the supply of printing media where printing composition is deposited may be adjusted.
The above-described embodiments of a method in accordance with the present invention may be modified to work with any number of additional supplies of print media where the printing device is configured to selectively feed any one of the supplies of print media into the printzone where printing composition is deposited on the selected supply of print media. Additionally, the supply or supplies of print media may comprise at least one sheet of print media in a print media input tray.
An embodiment of an apparatus in accordance with the present invention for use in a printing device, the printing device having a supply of print media and being configured to feed the supply of print media into a printzone where printing composition is deposited on the supply of print media, includes a sensor configured to detect the supply of print media and output a signal indicative of the detected supply of print media. The apparatus also includes a computing device coupled to the sensor to receive the signal indicative of the detected supply of print media. The computing device is configured to determine a median position of the supply of print media in the printzone based on a plurality of trials of feeding the supply of print media into the printzone. The computing device is further configured to adjust a position in the printzone for the supply of print media where printing composition is deposited based on the determined median position of the supply of print media in the printzone.
In the above-described embodiment of a apparatus in accordance with the present invention, the sensor may be configured to detect an edge of the supply of print media and output a signal indicative of the detected edge of the supply of print media. In such cases, the computing device is configured to determine a median position of the edge of the supply of print media in the printzone based on a plurality of trials of feeding the supply of print media into the printzone and to adjust a position in the printzone for the supply of print media where printing composition is deposited based on the determined median position of the edge of the supply of print media in the printzone.
The above-described embodiments of an apparatus in accordance with the present invention may be modified to work with any number of additional supplies of print media where the printing device is configured to selectively feed any one of the supplies of print media into the printzone where printing composition is deposited on the selected supply of print media. Additionally, the supply or supplies of print media may comprise at least one sheet of print media in a print media input tray.
An alternative embodiment of an apparatus in accordance with the present invention for use in a printing device, the printing device having a supply of print media and being configured to feed the supply of print media into a printzone where printing composition is deposited on the supply of print media, includes structure for determining a range of positions of the supply of print media in the printzone. The apparatus also includes structure for determining a median position of the supply of print media in the printzone and structure for adjusting a position in the printzone for the supply of print media where printing composition is deposited based on the determined median position of the supply of print media in the printzone.
In the above-described alternative embodiment of an apparatus in accordance with the present invention, the structure for determining a range of positions may determine the range of positions of an edge of the supply of print media in the printzone and the structure for determining a median position may determine the median position of the edge of the supply of print media in the printzone. In such cases, the structure for adjusting a position in the printzone may adjust the position in the printzone for the supply of print media where printing composition is deposited based on the determined median position of the edge of the supply of print media in the printzone.
The above-described alternative embodiments of an apparatus in accordance with the present invention may be modified to work with any number of additional supplies of print media where the printing device is configured to selectively feed any one of the supplies of print media into the printzone where printing composition is deposited on the selected supply of print media. Additionally, the supply or supplies of print media may comprise at least one sheet of print media in a print media input tray.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.